From UPSC perspective, the following things are important :
Prelims level : Himalayan rivers, Zanskar Padam
Mains level : Read the attached story
Indian researchers have studied rivers in Ladakh Himalaya, bringing out 35 thousand-year histories of river erosion and identified hotspots of erosion and wide valleys that act buffer zones.
Erosion hotspot: Ladakh region
- The Ladakh Himalaya forms a high altitude desert between Greater Himalayan ranges and Karakoram Ranges.
- The Indus and its tributaries are major rivers flowing through the terrain.
- The Zanskar River is one of the largest tributaries of the upper Indus catchment, draining orthogonally through highly deformed Zanskar ranges.
Zanskar: A major river in Ladakh
- Two prominent tributaries of Zanskar River are the Doda and Tsrap Lingti Chu, which confluence at Padam village in the upper valley to form the Zanskar River.
- Zanskar catchment was explored to understand the landform evolution in the transitional climatic zone, using morpho-stratigraphy and study of landforms like valley fill terraces, alluvial fans (triangle-shaped deposit of gravel, sand, and even smaller pieces of sediment, such as silt).
- Zanskar river makes a deep gorge in its lower reaches with the headwaters in upper Zanskar makes wide basin called as Padam.
- The basin stores large amount of sediments in form of fans and river terrace deposits
- The research suggested that the wide valley of Padam, with an area of 48 square km, in the upper Zanskar, has stored a vast amount of sediments in these landforms.
- Thus Padam valley is a hotspot of sediment buffering in the Zanskar.
Sediment study reveals the erosion
- The study suggested that most sediments were derived from Higher Himalayan crystalline that lies in the headwater region of Zanskar.
- It was found out that dominant factors responsible for sediment erosion were deglaciation and Indian Summer Monsoon derived precipitation in the headwaters despite the presence of a geomorphic barrier (the deep, narrow gorge).
Significance of the study
- The scientists have traced where the rivers draining Himalaya and its foreland erode the most and identify the zones that receive these eroded sediments and fill up.
- The study will help understand river-borne erosion and sedimentation, which are the main drivers that make large riverine plains, terraces, and deltas that eventually become the cradle to evolving civilizations.
- It will also help study the dynamics of devastating floods created by these Himalayan rivers in recent times.
- Thus, the understanding of water and sediment routing becomes crucial while developing infrastructure and for other development works in the river catchment area.